Myasthenia gravis

Oesophageal atresia (OA) encompasses a group of congenital anomalies comprising of an interruption of the continuity of the oesophagus with or without a persistent communication with the trachea. In 86% of cases there is a distal tracheooesophageal fistula, in 7% there is no fistulous connection, while in 4% there is a tracheooesophageal fistula without atresia. OA occurs in 1 in 2500 live births. Infants with OA are unable to swallow saliva and are noted to have excessive salivation requiring repeated suctioning. Associated anomalies occur in 50% of cases, the majority involving one or more of the VACTERL association (vertebral, anorectal, cardiac, tracheooesophageal, renal and limb defects). The aetiology is largely unknown and is likely to be multifactorial, however, various clues have been uncovered in animal experiments particularly defects in the expression of the gene Sonic hedgehog (Shh). The vast majority of cases are sporadic and the recurrence risk for siblings is 1%. The diagnosis may be suspected prenatally by a small or absent stomach bubble on antenatal ultrasound scan at around 18 weeks gestation. The likelihood of an atresia is increased by the presence of polyhydramnios. A nasogastric tube should be passed at birth in all infants born to a mother with polyhydramnios as well as to infants who are excessively mucusy soon after delivery to establish or refute the diagnosis. In OA the tube will not progress beyond 10 cm from the mouth (confirmation is by plain X-ray of the chest and abdomen). Definitive management comprises disconnection of the tracheooesophageal fistula, closure of the tracheal defect and primary anastomosis of the oesophagus. Where there is a "long gap" between the ends of the oesophagus, delayed primary repair should be attempted. Only very rarely will an oesophageal replacement be required. Survival is directly related to birth weight and to the presence of a major cardiac defect. Infants weighing over 1500 g and having no major cardiac problem should have a near 100% survival, while the presence of one of the risk factors reduces survival to 80% and further to 30–50% in the presence of both risk factors.     

Restoring the balance: immunotherapeutic combinations for autoimmune disease

Autoimmunity occurs when T cells, B cells or both are inappropriately activated, resulting in damage to one or more organ systems. Normally, high-affinity self-reactive T and B cells are eliminated in the thymus and bone marrow through a process known as central immune tolerance. However, low-affinity self-reactive T and B cells escape central tolerance and enter the blood and tissues, where they are kept in check by complex and non-redundant peripheral tolerance mechanisms. Dysfunction or imbalance of the immune system can lead to autoimmunity, and thus elucidation of normal tolerance mechanisms has led to identification of therapeutic targets for treating autoimmune disease. In the past 15 years, a number of disease-modifying monoclonal antibodies and genetically engineered biologic agents targeting the immune system have been approved, notably for the treatment of rheumatoid arthritis, inflammatory bowel disease and psoriasis. Although these agents represent a major advance, effective therapy for other autoimmune conditions, such as type 1 diabetes, remain elusive and will likely require intervention aimed at multiple components of the immune system. To this end, approaches that manipulate cells ex vivo and harness their complex behaviors are being tested in preclinical and clinical settings. In addition, approved biologic agents are being examined in combination with one another and with cell-based therapies. Substantial development and regulatory hurdles must be overcome in order to successfully combine immunotherapeutic biologic agents. Nevertheless, such combinations might ultimately be necessary to control autoimmune disease manifestations and restore the tolerant state.KEY WORDS: Tolerance, Autoimmune, Biologic     

Novel immunotoxin: a fusion protein consisting of gelonin and an acetylcholine receptor fragment as a potential immunotherapeutic agent for the treatment of Myasthenia gravis

In continuation of our attempts for antigen-specific suppression of the immune system [I.L. Urbatsch, R.K.M. Sterz, K. Peper, W.E. Trommer, Eur. J. Immunol. 23(1993) 776-779] a novel fusion protein composed of amino acids 4-181 of the extracellular domain of the alpha-subunit of the human muscle acetylcholine receptor and the plant toxin gelonin was expressed in Escherichia coli. The fusion protein formed inclusion bodies but could be solubilized in the presence of guanidinium hydrochloride. After a simple two step purification and refolding procedure, it exhibited a native structure at least in the main immunogenic region as shown by antibodies recognizing a conformational epitope. Half maximal inhibition of translation was achieved at 46 ng/ml as compared to 4.6 ng/ml for native and 2.4 for recombinant gelonin. Its use as therapeutic agent for the treatment of Myasthenia gravis was investigated in an animal model. Female Lewis rats were immunized with complete acetylcholine receptor from the electric ray Torpedo californica and developed thereafter experimental autoimmune M. gravis. Quantitative assessment of the disease was achieved by repetitive stimulation of the Nervus tibialis. Rats showed no symptoms of M. gravis, neither visually nor electrophysiologically after treatment with the fusion protein as determined one and seven weeks after the second application. This approach may also be useful for the therapy of further autoimmune diseases by substituting other autoantigens for the AchR fragment in the fusion protein.     

Myasthenia gravis and the thymus gland.

Six skin cancer detection clinics were held at a county fair booth in Turlock, California during August, 1973. Examination of sun-exposed skin areas in 605 people showed potential skin cancer in 28.6 percent of people 25 years of age or older. Of the people examined, 135 were referred to their own physicians for follow-up diagnosis and treatment of skin lesions.     

Myasthenia gravis associated with penicillamine treatment for rheumatoid arthritis.

Four patients with rheumatoid arthritis (R.A.) developed myasthenia gravis after taking penicillamine. In one patient withdrawal of the drug was followed by spontaneous remission of the myasthenia, and in two the dose of anticholinesterase was subsequently reduced. In the fourth patient continuing penicillamine treatment was associated with increasingly severe myasthenic features, but on withdrawal of the drug these resolved. As myasthenia gravis rarely complicates R.A. its onset in these patients shortly after the start of penicillamine treatment suggested that penicillamine may have precipitated this condition.